do you lose benefits of templates if you no longer qualify for it?

[Crichton]

as it is LA -

No, it is not. It has no entry/field at all for Level Adjustment, which, according to the general rules for Template entries/fields, means the template doesn't modify that entry from what the original creature had.

i looked it up, the la:- is the ghast so that doesnt count.
but the template doesnt have a la entry. does that default to - or 0? if it defaults to - your right but if not your not.
.

As you say, the LA: - entry is for the sample Ghast, but the actual Template, on page 162, has no entry for LA. The default isn't either LA:0 or LA:- though. The default for Templates is that if a particular entry is missing from the Template, then the Template doesn't change that aspect of the original creature.

if a template does not cause a change to a certain statistic, that entry is missing from the template description