The suggestion by C Monsour is good, but not the only option.
While the heart is anatomically cor, it is not always the best translation in a setting like this.
See this separate question for translating "heart" in a figurative sense.
There are many kinds of Latin, and the idiomatic choice depends somewhat on the chosen style.
In classical Latin pectus appears to be more idiomatic than cor although it literally means "chest".
If you want the style to be more Christian than classical, then cor works better than pectus.
This is a style choice you have to make.
The last part could be semper in pectoribus, "always in [the] hearts".
In English you need either an article or a possessive pronoun, but in Latin neither is needed.
I think it is clear enough from context what is meant, and you might even like the idea of not specifying all the hearts that remember them.
It is certainly not wrong to add nostris if you want to specify "our".
The original English triplet is not symmetric.
The first two have a participle (loved, remembered) while the third one has a prepositional phrase (in hearts).
Therefore it is reasonable to take the liberty to move these statements between these two types to find a fluent translation.
I bring this up because "always remembered" could be nicely rendered as semper in memoria, literally "always in memory".
This word should be familiar to many from the phrase in memoriam, and is therefore likely to evoke a fitting reaction.
If we are talking about memories and hearts, it makes sense to have them in a similar form.
Either several memories and several hearts or a single memory and a single heart.
This harmony is not necessary, especially if the two are not next to each other, but something to consider.
The singular would focus more on the individual experience of anyone who reads the inscription, whereas the plural would be more collective.
I would vote for plural, but the choice is of course yours.
The singulars would be memoria, pectore and the plurals memoriis, pectoribus.
The first part "always loved" is very naturally semper amati.
The masculine plural amati is the right choice for a group of people that contains a male.
I tried to find a way to phrase it also as "always in [something]", but found nothing suitable.
The asymmetry of the original remains but is slightly changed.
You can try changing the order of the three elements to see if it sounds better.
Swapping the first two works to my ear.
So, my suggestion would be:
Semper amati, semper in memoriis, semper in pectoribus.
Latin inscriptions are often made with capital letters and U written as a V.
In this style, it would look like:
SEMPER AMATI, SEMPER IN MEMORIIS, SEMPER IN PECTORIBVS.
My personal favorite among the options arising seems to be inscribing something like this:
SEMPER IN MEMORIA
SEMPER IN PECTORIBVS